This application is based on and claims the benefit of European Patent Application No. 00402595.3 filed Sep. 20, 2000, which is incorporated by reference herein.
The invention relates to an elongate object with at least one transmission element arranged in a core thereof, in which an outer sheath of insulation material is applied over the core.
xe2x80x9cElongate objectsxe2x80x9d in terms of the invention may be electrical cables or lines, optical cables or lines, or pipelines. Accordingly, the transmission element is an electrical conductor, an optical conductor, or a pipe for conducting fluids. All these objects have been known for many years and are commercially available. They have the common feature that they are provided with an outer sheath made of an insulating material, for instance polyethylene or polyvinyl chloride. Since the technical problem to be solved by the invention is the same in all cases, the following description relates to cables, but vicariously also applies to lines and pipelines.
At least the cable cores are constructed in such a way that they are optimally suited to their purpose. In principle, this also applies to the outer sheath. The selection of the sheath""s material, however, often involves compromises with respect to its properties, since, for instance, an electrically suitable material is not necessarily suitable if the cable is to be used in a rough environment where it is exposed, for example, to substantial friction or chemical influences. An example of this type of application is automotive engineering. In this case the sheath""s insulating material must, in particular, be abrasion resistant and resistant against oil and gasoline. For other applications of the cable, the sheath will require different properties, for instance low friction and a hard surface, or heat resistance and good behavior in fire. For different applications, even if the cables have an identical core, they are provided with sheaths of different materials, which in many cases are applied to the core with different machines.
An object of the invention is to design the initially described cable in such a way that it can be adapted to different requirements at little cost.
According to the invention, this object is attained by providing the sheath with a coating of a cross-linkable insulating material, which is very thin compared to the thickness of the sheath, and the individual properties of which satisfy the particular cable application.
Such a cable can be constructed, without limitation, solely for the respective transmission purpose. This applies to both the core with at least one transmission element and, in particular, to the sheath the material of which can, for instance, be exclusively selected for specific properties. Regardless of the subsequent application, all cables can be equipped with an identical outer sheath. Each cable is finally provided with a very thin coating to make it suitable for the application for which it is intended. Said coating can be very thin compared to the sheath thickness, so that the increase in the outside diameter of the cable is insignificant. The material of this coating can be readily adjusted to meet the properties required by the exterior of the cable sheath, i.e., for instance, high abrasion resistance or oil resistance. Very little material is required for the coating, which may be applied to the cable sheath by processes known per se.